April 8, 2017

1 - Mulberry trees which have been pollarded, or pseudo-pollarded, may grow if pollarding ceases, but they may also become hazardous trees.

Yard and Garden April 8, 2017

Q.

We have 9 mulberry trees that were pollarded in the past. Because pollarding causes many long branched to develop, I am wondering what the best pruning practice would be for maintaining the trees in the future.

- Ralph K.

A.

If proper pollarding technique was used throughout the time the tree was pollarded, you may find it most appropriate to continue pollarding. However, proper pollarding is not common. In most cases, for a properly pollarded tree, the process began when the tree was about three years old and branches cut were only 1 inch in diameter. Once pollarding has begun, the branches produced at the enlarged "knuckle" should be removed without leaving a stub every one or two years. This allows the tree the best opportunity to protect itself and close the pruning wound. Cutting larger branches and leaving stubs increase the potential for disease entry and damage to the tree.

If you wish to terminate pollarding because it had already terminated, because it was not pollarded correctly from the beginning, or because you wish to reduce the labor required by pollarding, you are fortunate that the tree is a mulberry. Many trees especially when grown in New Mexico are severely stressed by pollarding and may do poorly while pollarded and afterwards, but mulberry trees are often able to tolerate such treatment. If you do, indeed, wish to stop pollarding you should thin the number of branches coming from the knuckle to one or a few. Be aware that branches produced in response to pollarding are not strongly attached to the tree. They are held by the numerous other branches, but over time may fall even if you do not thin the branches. Thinning will increase the possibility of branch failure and falling branches. As the branches enlarge after you terminate pollarding the chances for branch failure increases. Make sure the branches are not over your house, your car, picnic tables and other outdoor sitting areas, and especially not over children's and pet's play areas.

Trees in areas where falling branches may cause damage or harm to people and pets, you may consider removing the trees for safety. They may be replaced by new trees which are not pollarded. If the trees are away from areas where they can be hazardous, then thinning the branches, proper watering and providing of nutrients to the trees may be the choice that is best for you.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

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For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.